1. Field of the Invention
The present invention generally relates to a virtual storage control apparatus for controlling a virtual storage and a virtual storage control program for use to realize the virtual storage control apparatus, and more particularly to a virtual storage control apparatus that realizes the data integrity for the data updated successively with the passage of time, and a virtual storage control program for use to realize the virtual storage control apparatus.
2. Description of the Related Art
Since it is apprehended that the file data is rewritten due to a malicious access or false operation, it is necessary to prevent the file data from being rewritten due to malicious access or false operation.
Conventionally, the file is made in the form of WORM (Write-Once, Read-Many) to prevent the file data from being rewritten due to malicious access or false operation (for example, refer to patent document 1: Japanese Patent Application Laid-Open No. 2006-092276).
On the other hand, a technique of a virtualization switch that operates to appear to a host apparatus as if a plurality of real disks were one disk (virtual disk) is employed.
In this virtualization switch, the correspondence between the LBA (Logical Block Address) of a virtual disk and the LBA of a real disk is managed, and access is made by specifying the storage block of the real disk associated with the storage block of the virtual disk designated by the host apparatus based on its correspondence, whereby a plurality of real disks appear to be one virtual disk (for example, refer to non-patent document 1: Storage ETERNUS VS900 Virtualization Switch: Fujitsu (retrieved on Jun. 5, 2006).
A user owns the resources of data that should not be lost or altered such as official documents, web site or access log. Therefore, it is required that the integrity of the data is implemented.
On the other hand, when a plurality of real disks distributed over a network are employed, it is very convenient to use a technique of virtualization switch to construct a system because the plurality of real disks appear to be one disk.
In the background of this situation, when the system is constructed using a virtualization switch, it is required to implement the integrity of the data stored in the real disk and owned by the user.
A method for realizing the integrity of data involves making the file in the form of WORM. Employing this method, when there is a write request for writing data in a storage block where the data is once written, the write request is not accepted. Consequently, the integrity of the data stored in the real disk and owned by the user can be achieved.
However, there is a problem that the integrity of data updated successively with the passage of time cannot be assured by this method.
Since the write request for writing data in the storage block in which the data is once written is not accepted, the integrity of data updated successively with the passage of time cannot be achieved.